Police said Erin Nicole Thorne, 28, of Arnold, was charged with one count of displaying obscene matter to minor and one count of child porn solicitation.

Thorne is an English teacher and basketball coach at the school. She's been put on administrative leave since Anne Arundel County Public School officials said an anonymous caller contacted them regarding a possible inappropriate relationship between Thorne and a male student who graduated from the school in the spring of 2011.

Police who took over the case said they learned from the former student that he and Thorne formed a friendship in September 2010 during his senior year.

Police said at one point during that fall semester, Thorne began sending the teen sexually explicit text messages, and from there, the two began talking regularly on the phone. The pair continued to exchange sexually explicit text messages and images at Thorne's request before the student was 18 years old, police said.

Authorities said the two eventually engaged in sexual activity after the student turned 18 while he was still a student at the school.

Police said Thorne turned herself in to the Eastern District police station around 1 p.m. Tuesday.

"I think it was certainly disappointing and, frankly, appalling that a teacher would allow herself to be put in a situation that charges like this can come forth," said police spokesman Justin Mulcahy. "It's certainly not indicative of the great work that our teachers do across the county every day."

"As a father, I am deeply disturbed that someone whose obligation it is to care for the welfare of children could put themselves in a position to bring about charges such as these. There is a legal process here that must be allowed to play out, but our Board is charged with doing everything we can to protect every one of the nearly 78,000 children in our school system. We intend to see that we carry out that duty," Board of Education President Andrew Pruski said.

"The kind of behavior that Erin Thorne is charged with engaging in cannot be tolerated at any school in our county, or in our nation for that matter. Preying on children in any way should not be excused for a single moment," Superintendent Kevin Maxwell said.

"We have a great school and a great community that supports our Broadneck students in their individual quests for excellence. It saddens me that charges like this cast a negative light on our school and tarnish the incredible work that our staff, parents, and students do on a daily basis. We are a resilient school, however, and I have no doubt that we will band together so that our students continue to excel," Broadneck High School Principal David Smith said.